The manufacture of power transmission members, to which this invention relates, has utilized a pair of slidable toothed racks and a rotatable toothed mandrel to develop the tooth form in the periphery of an annular or tubular workpiece. A machine has been provided for rotatably supporting the mandrel between the pair of toothed racks which are mounted for sliding motion past opposite sides of the mandrel on slide members.
The McCardell U.S. Pat. No. 3,214,751 issued Nov. 2, 1965 of common assignee herewith discloses a machine of this type having a rotatable cylindrical mandrel and a pair of tooth forming racks disposed on opposite diametrical sides of the mandrel and slidable in opposite directions against a tubular workpiece on the mandrel. A smooth (not toothed) mandrel is employed since tooth elements are to be formed on the outside of the tubular workpiece.
The Killop U.S. Pat. No. 3,982,415 issued Sept. 28, 1978 describes an apparatus for splining a cup-shaped power transmission member wherein a pair of slidable tooth forming racks are employed in conjunction with a hollow, toothed mandrel supported rotatably at opposite open ends by first and second arbors with the annular end wall of the cup-shaped member engaged against the end of the mandrel. The Killop U.S. Pat. No. 4,028,922 issued June 14, 1977 discloses a somewhat similar apparatus adapted for spining a cup-shaped power transmission member wherein the hollow mandrel is affixed to the machine headstock spindle and the open sleeve of a cup-shaped workpart is slid onto the free mandrel end. The sleeve of the workpart is splined along its length to the open end where axial depressions may be formed by the racks. The rack teeth forming the depressions are said to support the open end during splining to reduce out of roundness thereof.
The Jungesjo U.S. Pat. No. 4,155,237 issued May 22, 1979 also discloses a splining machine including a pair of slidable tooth forming racks and a hollow, toothed mandrel. The machine further includes a workpiece unloading member extending from the headstock spindle side of the machine through the hollow mandrel to engage a splined workpart, a slidable loading member on the tailstock side of the machine including a workpart clamp to hold the workpart on the end of the mandrel during spining and rotatable with the mandrel for this purpose, a rotatable indexed mechanism with U-shaped workpart retainers to feed individual parts between the loader and mandrel, and a guide tube between the loader and mandrel for guiding workpiece movement toward and away from the mandrel.
A splining machine is also described in the Hooker U.S. Pat. No. 1,510,889 issued Oct. 7, 1924. In this patent, a cup-shaped sheet metal blank is mounted on a rotatable toothed mandrel with the mandrel received in the open sleeve of the blank and the end wall of the blank engaged against the end of the mandrel by a threaded nut. A hob or rack with gear teeth thereon is mounted such that it can be reciprocated and rotated relative to the mandrel synchronously therewith to intermesh the teeth of the mandrel and hob with the sleeve of the blank therebetween.
And, the Lindell U.S. Pat. No. 3,473,211 issued Oct. 21, 1969 illustrates a machine for rolling internal teeth in the sleeve of a cup-shaped sheet metal power transmission member while the sleeve is supported and clamped on a stationary toothed mandrel. A set of revolving rollers engages the exterior surface of the sleeve to roll the sleeve into the mandrel teeth to form gear type teeth. Also see the McCardell U.S. Pat. No. 3,062,077 issued Nov. 6, 1967 for the pressure forming of internal teeth on a workpart.
The corrugation of tubular or cup-shaped blanks to simultaneously form internal and external tooth-like profiles by a rolling process employing a rotatably mounted toothed mandrel and a pair of rotating dies is known as shown, for example, in the Mason U.S. Pat. No. 76,220 issued Mar. 31, 1868, the Greis et al. U.S. Pat. No. 3,407,638 issued Oct. 29, 1968, the Kiplinger U.S. Pat. No. 3,630,058 issued Dec. 28, 1971 and the Anderson U.S. Pat. No. 4,045,988 issued Sept. 6, 1977.
However, to-date prior art workers have had difficulty using the types of machines and methods described hereinabove in manufacturing a splined cup-shaped power transmission member, such as a clutch hub, within the well known six or eight sigma tolerance which includes total part print tolerances. In particular, prior art workers have had difficulty with respect to the axially extending splines or teeth on the sleeve portion and especially in meeting the specific tolerance limiting taper of the splines along the longitudinal axis of the sleeve prescribed by users of the parts, such as automobile manufacturers. This problem has frequently been referred to as "bellmouthing" of the sleeve characterized by an outward tapering of the splined sleeve in a longitudinal or axial direction from the annular end wall toward the open end of the sleeve. A typical tolerance for "bellmouthing" has been set as 0.016 inch for a particular clutch hub for power transmissions. Furthermore, it has been difficult to provide the desired longitudinal tooth tolerance (bellmouth tolerance) and at the same time maintain the proper roundness tolerance for the cylindrical oil seal surface or sleeve of the clutch hub. A typical tolerance for oil seal surface roundness has been set as 0.006 inch for the clutch hub just mentioned. The oil seal surface is typically connected to the sleeve portion of the power transmission member by a so-called transition region which heretofore has not been splined or otherwise substantially deformed in the splining process since past experience indicated that splining of the transition region could increase out of roundness of the oil seal surface.
Clutch hubs of the type of interest are described in the aforementioned Killop U.S. Pat. No. 3,982,415.